Annually in the US, 6 million patients present to emergency departments with acute chest pain or related complaints. (1) Most patients with acute chest pain presenting to emergency departments undergo an evaluation for possible acute coronary syndrome (ACS), yet the vast majority does not have this disease process. After exclusion of myocardial infarction (MI) with serial cardiac necrosis biomarkers, practice guidelines recommend further evaluation of patients with possible ACS with stress testing or coronary CT angiography (CCTA). (2) This practice is currently necessary to prevent the discharge of patients with unstable angina, but leads to a large number of negative tests. A biomarker is needed to predict patients likely to have underlying coronary artery disease (CAD) among patients with acute chest pain. A biomarker better able to identify patients likely to have coronary disease could improve testing efficiency by either reducing pretest probability below the testing threshold, or by guiding selection of the cardiac imaging modality.
Traditional cardiac risk factors, such as smoking, diabetes, and hypercholesterolemia, have been shown to correlate strongly with the long-term risk of developing coronary atherosclerosis. (3-5) In patients with acute chest pain, these risk factors have been shown to be only weak predictors of cardiac chest pain. (6) The rationale for this apparent discrepancy relates to the importance of the clinical history and the presence of acute chest pain being a much stronger relative predictor for symptomatic disease than these traditional risk factors.